I misread the original post and didn't realise that the message was deleted. My advice was given as a last resort measure as RedElephant has made it clear that the Police will not take any action. As I mentioned in my original post, ideally the Police should perform any examination required.
pbeardmore, thank you for the recommendation. With regards to your concern (and Jonathan's as well), I felt that it was only fair to provide the general outline of events since I was asking for help—something I explained in the original post. Since I've been careful not to give any identifying information about the case, I don't feel that I've compromsied the victim's privacy. Believe me, this type of crime is VERY common in New Zealand; the case in question didn't even make the local news.
I also planned to delete the bulk of the post once its job was done, which I have now done.
Thanks again to everyone who responded. Your help is very, very appreciated.